[Editor's note: This is Part III of an article reprinted from
Annales d'Otolaryngologie et de Chirurgie Cervico-Faciale [*], Part
I--"Phylogenesis and physiology," appeared in the November2000
issue of Ear, Nose & Throat Journal and included the references for
the entire three-part article. Part II--"Causes, diagnosis, and
management" appeared in the December 2000 issue of Ear, Nose &
Throat Journal.]

Indications for surgical treatment

Surgical treatment depends on the severity of symptoms, the general
health of the patient, and the patient's wishes in terms of voice
quality. [51] Aspiration is a major factor in initial evaluation and
surgical indication. Aspiration pneumonia is life-threatening, with high
mortality, especially after lung surgery. [65] Glottic insufficiency
decreases the effectiveness of cough, so the treatment of URLNP in
patients suffering from chronic bronchitis is aimed at preventing
complications of insufficient lung clearance. Patients with poor general
health unrelated to pulmonary disease may also benefit from early
surgery, avoiding pulmonary complications of URLNP.

Aspiration may occur whatever the origin of the URLNP, but it seems
to occur more frequently and more severely in cases of vagal nerve
lesions. Sensation in the pharynx and larynx is diminished in vagal
lesions by damage to the internal branch of the SLN and the pharyngeal
plexus. In this case, paresis or paralysis of the pharyngeal constrictor
muscles and the velum contributes to dysphagia and aspiration.

Management of aspiration in URLNP has three levels: adaptation of
food, swallowing exercises, and VC medialization. First, liquids should
be excluded from the diet. Water in jellified form may be consumed if
little or no aspiration is detected. If general health and pulmonary
function are excellent and aspiration occurs rarely (type I or rarely
type II, according to Pearson's classification [66]), swallowing
therapy may suffice to avoid complications. Therapy includes rotating
the neck toward the paralyzed side to direct the bolus to the piriform
sinus on the healthy side, partial cervical flexion during swallowing,
"double swallow," and other maneuvers. [45] If aspiration
presents a major health risk, if it occurs for each swallow, or if for
any other reason it is poorly tolerated, surgery is indicated.

In the absence of aspiration, surgical intervention depends on the
patient's profession (voice professional) and his or her wishes in
terms of voice quality. The social and professional role of voice must
be taken very seriously. Once surgery has been decided, the timing and
the type of procedure need to be determined.

Timing of surgery

Timing relative to the onset of URLNP depends on the severity of
symptoms and on the mechanism of the neural lesion. In high vagal nerve
resection (in skull base surgery, for example), symptoms are often
severe and chances of spontaneous recovery are extremely low. Early
surgical treatment, or even immediate medialization, performed at the
time of vagal resection is often recommended. [51] In this case,
however, the difficulty lies in estimating the degree of medialization
necessary to compensate for ulterior VC atrophy.

For resection of the RLN, symptoms vary in severity and surgical
indications vary. Early surgery is justified in cases of severe
aspiration or for vocal necessity (voice professionals), while awaiting
an eventual spontaneous compensation or reinnervation. If the RLN was
sectioned but surgical anastomosis was performed immediately, severity
and evolution are unpredictable. Again, if symptoms are severe, surgery
is indicated despite an eventual spontaneous reinnervation or
compensation.

If the type of nerve damage is unknown or if the paralysis is well
tolerated, a waiting period of 12 months is indicated to allow for
spontaneous recovery of motion, favorable synkinesis, or laryngeal compensation. [37,51] Again, if the mechanism of nerve damage is unknown
and the symptoms severe, early surgery is indicated. [51] A reversible
procedure is recommended in cases of ulterior spontaneous recovery,
favorable synkinesis, or compensation. If little or no voice improvement
is noted after the 12-month waiting period, a "permanent"
surgical procedure should be considered according to the patient's
wishes in terms of voice quality.

Type of surgical procedure

The procedure depends on the general health of the patient, his or
her needs or wishes in terms of voice quality, the glottic
configuration, and the experience of the surgeon. Most medical teams
recommend preoperative evaluation by a voice specialist and a speech
therapist. [45,51] Voice recordings and objective acoustic and
aerodynamic evaluation are performed. The speech therapist aids in
evaluating the patient's vocal needs and can initiate breathing
exercises.

The preoperative physical workup is designed to determine glottal configuration during phonation. Video documentation using fiberoptic or
telescopic laryngoscopy and/or stroboscopy is recommended. The type of
glottic gap should be noted: membranous (elliptical) or membranous and
cartilaginous (triangular). [45] The relative level of the vocal folds
on phonation, with a lower or higher paralyzed fold, should be
evaluated. Glottic configuration must be precisely determined because
the various surgical techniques address these configurations
differently.

Techniques for VC medialization belong to four general categories:
medialization thyroplasty, arytenoid adduction, intracord injection, and
laryngeal reinnervation. Each technique has its particular indications,
advantages, disadvantages, and complications.

Medialization thyroplasty

Introduction. In 1915, Payr was the first to report external VC
medialization using a thyroid cartilage flap. [67] Isshiki et al in 1974
were the first to describe the technique in detail and to employ it for
treating glottic incompetence. [9] The technique is now known as the
Isshiki type I procedure (the other procedures described by Isshiki are
not employed for treating URLNP). Thyroplasty consists of introducing an
implant through a window in the thyroid cartilage to medialize the VC
and the vocal process.

Technique. External thyroplasty should be performed using local
anesthesia, with or without light sedation. This allows precise
placement of the implant according to the intraoperative voice result.
Performed under general anesthesia, the phonatory results are
unpredictable, and an eventual endotracheal tube impedes correct
medialization. During the procedure, fiberoptic laryngoscopy is
performed, allowing intraoperative visualization of the laryngeal
configuration at rest and during phonation.

A horizontal cutaneous incision 5 to 6 cm long is made at the
midlevel of the thyroid cartilage on the paralyzed side. [45] The
superior subplatysmal flap is raised to the superior border of the
thyroid cartilage and the inferior flap to the superior border of the
cricoid cartilage. The midline is incised and the strap muscles reclined laterally. The external thyroid perichondrium is then elevated from the
midline laterally to the posterior border of the thyroid ala.

The VC is located midway between the thyroid notch and the inferior
border of the thyroid cartilage. It is currently recommended to
delineate the thyroid window in a low position, as the contralateral normal VC adducts and is lowered during phonation. [44] The risk of
implanting the prosthesis in the ventricle is decreased with a low
window placement as well. Tucker et al [68] advise placing the window 5
mm above the inferior border of the thyroid cartilage, while Netterville
et al [69] advise 3 mm. Hoffman and McCulloch place the window at the
junction between the superior two-thirds and the inferior one-third of
the thyroid ala along the oblique line. [45]

The anterior border of the window should remain 5 to 10 mm from the
midline to avoid damage to the anterior commissure or extrusion of the
implant, the anterior VC being relatively thin. [67] The posterior limit
should be 10mm from the posterior border of the thyroid ala. [68] For
all the techniques, the window is located just above the inferior
tubercule, an external anatomic landmark for the vocal process of the
arytenoid.

The window is outlined on the thyroid cartilage using
electrocautery or methylene blue. For the Montgomery thyroplasty
technique, special instruments are employed to place and outline the
window . [70] Incision of the cartilage is performed using a scalpel
(for nonossified cartilage), a diamond burr with continuous irrigation,
or with a microsaw. [70] The shape of the window depends on the type of
implant: rectangular for silicone or hydroxyapatite implants, round for
the Gore-Tex ribbon implants. Contrary to some initial reports, it is
not necessary to retain the resected fragment of cartilage. In fact, it
is not recommended due to secondary resorption or displacement of the
fragment, with unpredictable vocal results. [68]

After drilling the window, the internal perichondrium is delicately
raised from the internal surface of the thyroid ala 2 to 4 mm in all
directions. Incision of the perichondrium is recommended by several
authors; in fact, it seems to be necessary for correct implant
positioning. [45,51,69,71] Netterville et al recommend perichondrial incision along the superior, posterior, and inferior borders of the
window, creating an anteriorly based perichondrial flap. [69]
Perichondrial incision nearly always causes bleeding in the TA muscle,
which must be carefully controlled using bipolar cautery.

The implant type depends on the experience and choice of the
surgeon and eventually the implant cost. The hypothetical ideal implant
is biologically inert, presculpted to the adequate shape and size, easy
to place, reversible, and readily available at a low cost. [45] Silastic (silicone polymer), hydroxyapatite, and Gore-Tex (expanded
polytetrafluoroethylene or ePTFE [72]) are currently employed for
implants. The shape varies from rectangular, to rectangular with an
anterior triangular pyramid (for medialization close to the anterior
commissure) or a posterior triangular pyramid (for medialization of the
vocal process of the arytenoid), or both. Some implants are preshaped,
[70] while others must be shaped intraoperatively. Gore-Tex is in the
form of a cardiac patch that is cut into a ribbon.

A slight overcorrection is recommended to compensate for resorption
of the postoperative laryngeal edema. [73] Overcorrection is also
recommended in cases of early surgery due to later muscular atrophy that
can cause poor voice quality despite the implant. Maximal medialization
should be obtained at the posteroinferior corner of the window,
corresponding to the vocal process. [69] Depth at this point is measured
by pushing the vocal process (with a microelevator or with a special
measuring instrument) while the patient phonates. This depth is modified
until the optimal vocal result is obtained. Depth corresponds to the
width of the implant. Placement of the implant should be rapid in order
to adequately evaluate voice quality before the onset of laryngeal
edema. [51]

Hemostasis is checked and the incision is closed in layers on a
suction drain, which is maintained for 24 hours. Perioperative steroids
(prednisone 1 mg/kg) is recommended by some authors. [71,73] Most
authors also recommend prophylactic oral antibiotics for 5 to 7 days
postoperatively. [71-73] Tucker et al [68] and Montgomery et al [71]
recommend a 24-hour hospitalization postoperatively in order to diagnose
and treat possible complications, especially dyspnea due to laryngeal
edema or hematoma.

Advantages and disadvantages. Thyroplasty is a relatively simple
technique to learn and results are rapidly reproducible, unlike Teflon
injection, for example, in which results are unpredictable without
considerable experience. Local anesthesia permits physiologic vocal fold
motion during phonation intraoperatively, allowing precise implant
positioning and shaping. [74] The technique is theoretically reversible,
but fibrosis and foreign body reaction may permanently affect voice even
after implant removal. [75,76]

It seems that thyroplasty does not sufficiently close the posterior
glottis, and thus it may yield disappointing results if used alone in
cases of a large posterior glottal gap. [45,52] The degree of
medialization of the anterior glottis and the site of maximal
medialization are, however, adjustable intraoperatively [74] or later in
cases of voice modifications. [72]

The Montgomery implant is radiographically opaque, allowing
visualization on standard neck x-ray in cases of displacement or
extrusion. [70,71] The major advantages of preformed implants are their
rapid placement and their secure locking system. But the drilling of the
thyroid window needs to be of a precise shape and size, and the cost of
these implants is high. Sculpting a Silastic block intraoperatively is
difficult and increases the duration of surgery. Some have recommended
partial initial carving before sterilization of the Silastic block to
partially decrease sculpting time, [45] but exact sizing and shaping is
still difficult. Gore-Tex is much simpler in that it requires no precise
sculpting, window drilling, or specific instrumentation. [72] A
4-mm-wide ribbon is cut out of a cardiac patch and inserted little by
little through around thyroplasty window, which can vary in shape and
size. The biocompatibility of Gore-Tex is well known after more than 20
years of use in cardiac surgery.

All of these biomaterials provoke a local inflammatory reaction.
This reaction seems to be less severe than with Teflon (see below).
Extrusion or displacement of the implant is always a risk. The
viscoelastic properties of these materials are radically different from
those of the normal vocal fold, [77] and thus they may interfere with
normal laryngeal vibration and alter voice quality. Finally, the
external approach leaves a cutaneous scar.

Indications. The reversibility of thyroplasty has not yet been
sufficiently demonstrated to consider it as a "temporary"
treatment. For this reason, early thyroplasty does not appear to be
recommended if spontaneous recovery is likely. The indisputable
indication is any stable, definitive paralysis without surgical
contraindications. In the case of a large posterior glottal gap,
thyroplasty alone may be insufficient and may be associated with
arytenoid adduction (see below). The choice of implant depends
especially on the personal experience of the surgeon.

Abnormal hemostasis and allergic reaction to local anesthesia are
the main contraindications to external thyroplasty. Previous laryngeal
surgery (cordectomy) and external-beam radiation to the larynx are
relative contraindications because of the increased risk of implant
extrusion and infection. [69] Previous Teflon injection is not a
contraindication, but scarring and changes in the mass and elasticity of
the VC due to Teflon will influence the vocal result. [73] Thyroplasty
following Teflon injection is technically difficult as well.

Complications. Laryngeal obstruction due to hematoma within the
first postoperative week is the most frequent and dangerous complication
of external thyroplasty, occurring in 2 to 10% of cases. [67,68,73]
Several reported cases were treated by emergency surgery for hemostasis
or by temporary tracheotomy. Postoperative laryngeal edema, occurring in
2 to 4% of cases, usually requires only hospitalization for surveillance
and steroid treatment. [71,73,74] Displacement and extrusion of the
implant are rare, [67,68] but can occur immediately postoperatively or
years later, especially after laryngeal trauma. [73]

Vocal results. For most authors, voice is excellent immediately
after surgery. Objective acoustic and aerodynamic parameters were
significantly improved in a group of 43 patients studied by McLean-Mus
et al. [78] During the first months, voice quality apparently
deteriorates slowly and stabilizes after approximately 3 months. [69,79]
Overcorrection is recommended to compensate for operative laryngeal
edema and for later VC atrophy. Satisfactory voice is obtained in 70 to
90% of cases. [67,73,74,80] Reintervention for implant adjustment
improved results to 94% for Cummings et al. [73]

Arytenoid adduction

Introduction. This technique was also first described by Isshiki et
al in 1978. [44] The aim is to pull the muscular process of the
arytenoid laterally, reproducing the mechanical effects of the TA and
LCA muscles and allowing physiologic motion at the cricoarytenoid joint.
The body of the arytenoid rocks medially and the vocal process is
adducted and lowered. This technique can be used alone or, as stated
above, in conjunction with external thyroplasty or vocal fold injection.

Surgical technique. Arytenoid adduction is ideally performed using
local anesthesia in order to adjust adduction according to
intraoperative phonation. The approach to the thyroid ala is the same as
for thyroplasty, with lateral or medial retraction of the strap muscles.
The goal is to expose the posterior border of the thyroid ala. The
insertions of the inferior constrictor muscle on the paralyzed side are
incised along the inferior one-third of the thyroid ala. The piriform
sinus mucosa is elevated in order to palpate the arytenoid cartilage and
its muscular process. The arytenoid is located approximately between the
anterior two-thirds and the posterior one-third of the thyroid ala.
Exposure can be improved by resecting a posterior band of thyroid
cartilage. [45,69,81] The muscular process is identified by following
the PCA muscle fibers from their cricoid insertions to the arytenoid.
One or two 3-0 or 4-0 Prolene sutures are placed through the muscular
process or in the pericartilaginous tissue. These su tures are passed
anteriorly through two small drill holes placed 5 to 10mm from the
midline in the inferior one-third of the thyroid ala with a Keith's
needle. The sutures are knotted at the anterior surface of the thyroid
cartilage, and the wound is closed in layers on a suction drain.

Advantages and disadvantages. Local anesthesia allows
intraoperative phonatory adjustment of the sutures. In theory, arytenoid
adduction is reversible if the cricoarytenoid joint remains intact. The
surgical technique is rather delicate and necessitates a certain amount
of training and experience. Adduction permits closure of the posterior
glottal gap, but little medialization of the membranous VC is obtained.
It is often necessary to associate thyroplasty or vocal fold injection.
[44,45]

Complications. Postoperative laryngeal edema is the most frequently
occurring complication, and it generally responds favorably to steroids
and hospitalization for surveillance. Laryngeal hematoma following
arytenoid adduction has never been reported in the literature. Suture
displacement is possible, [67] as is local wound infection and an
unaesthetic scar.

Results. Some authors systematically associate arytenoid adduction
and thyroplasty. [52,69] Recent studies have not shown a significant
difference in objective voice results between the two techniques
(jitter, shimmer, harmonics-to-noise ratio, phonatory airflow rate).
[82] This may also be due to the lack of sensitivity of these objective
parameters. The technique seems to have less favorable results in cases
of long-standing URLNP due to muscular atrophy and fibrosis. [45]
Initially, Isshiki et al opened the cricoarytenoid joint in order to
more easily place the sutures and in order to stabilize the adduction by
causing cricoarytenoid ankylosis. Hoffman and McCulloch, however,
recommend not opening the joint because of the risk of joint
destabilization and arytenoid prolapse into the laryngeal lumen. [45]
They also maintain that joint opening is not necessary for proper
adduction.

Vocal fold injection

Introduction. In 1910, Brunings was the first to describe the
technique of endoscopic vocal fold injection. He developed a gun-like
syringe still used today. [45,83] Teflon injection was first described
by Arnold in 1962, and it has been widely employed ever since. [84] The
injection is designed to increase vocal fold volume and, to a lesser
degree, medialize the vocal process. It must be performed within the
vocalis muscle so as not to traumatize the vocal ligament or the
superficial lamina propria, thus preserving the vibratory
characteristics of these structures.

Surgical technique. Injection methods differ essentially in the
substance injected. Silicone seems to be employed more frequently in
Japan, whereas Teflon (polytetrafluoroethylene [72]) is used in the U.S.
and in Europe. More recently, Gelfoam, collagen (human or bovine),
autologous fat, hydroxyapatite cement, and a new silicone suspension are
being investigated and employed. [76] The injection is most often
performed endoscopically, although transcutaneous injection has also
been described. Injection via indirect mirror laryngoscopy and a curved
needle is rarely performed due to the difficulty, the learning curve,
and the need for a high level of patient cooperation. [45]

The ideal material for injection would be, according to Arnold,
easily injected, perfectly biocompatible, and inert over the long term.
Such a material does not yet exist. Teflon, for example, is easy to
inject and has lasting effects in the larynx, but its biocompatibility
is limited, with frequent complications with time. Autologous fat is
easily injected and perfectly biocompatible, but it tends to be
reabsorbed with unpredictable long-term effects in the larynx. [85]

Teflon injection. The injection is performed with the patient under
general anesthesia with tracheal intubation or under simple sedation
with spontaneous breathing. Sedation allows for a better evaluation of
the volume to inject by asking the patient to vocalize intraoperatively.
However, the natural vocal fold motion during breathing may interfere
with precise placement of the needle. General anesthesia immobilizes the
larynx and is more comfortable for the patient. However, the tracheal
tube can interfere with needle placement and with vocal fold
medialization. Jet ventilation eliminates the disadvantages of both
techniques, but it is not without risk (pneumothorax and
pneumomediastinum). [83]

The laryngoscope should be placed just cranial to the vocal folds
so as not to artificially modify glottic configuration. The operating
microscope is not employed, as it gets in the way of the injector and
does not improve needle placement notably.

A Brunings' injector is filled with 3 ml of Teflon. Two
injections are made on the paralyzed side. The first is done 2 to 3 mm
lateral to the vocal process, while the second is placed 4 to 5 mm
anterior to the first in the TA muscle. Both injections are made at a
depth of 3 to 5 mm. [45] It is better to underinject Teflon, as
secondary removal is extremely difficult and damaging to the vocal fold.
Reinjection is always possible if the vocal result is insufficient.

Transcutaneous injection is made through the cricothyroid membrane,
passes deep to the subglottic mucosa, and enters the vocal fold without
penetrating into the laryngeal lumen. Correct needle placement is
followed and volume evaluated using fiberoptic laryngoscopy.

Autologous fat. In 1991, Mikaelian et al were the first to report
the use of autologous fat to treat glottic incompetence in URLNP. [86]
Fat is harvested from the thigh or abdomen using a cutaneous incision or
lipoaspiration under local or general anesthesia. If fat is harvested
via a cutaneous incision, it is necessary to remove the fibrous tissue
and blood vessels and to morcellate the fat. Most recommend rinsing the
harvested fat in saline to remove the blood and free fatty acids. Fat
harvested by an incision seems to have a longer half-life than fat
harvested by lipoaspiration. In addition, lipoaspiration is impossible
in some patients in poor general health with little body fat. [87] The
placement and depth of injection are identical to those for Teflon. It
is necessary to overcorrect when using autologous fat. [88] An injection
of 6 ml is generally sufficient to obtain a medial convexity. A
transcutaneous approach may also be employed.

Steroids are administered intraoperatively (1 mg/kg of intravenous
prednisone). Most authors also recommend oral antibiotics for 5 to 7
days postoperatively. Oral feeding is allowed several hours
postoperatively if no complication arises. Voice rest is not necessary.
[86]

Advantages and disadvantages. Teflon and autologous fat are
inexpensive, as compared with collagen and the new biomaterials, and
their effects in tissues are well documented. Whichever implant material
is used, the technique is easy and quick to perform ([less than or equal
to]15 min), but it requires general anesthesia or heavy sedation for
direct laryngoscopy. The injection increases the volume of the paralyzed
vocal fold and, to a lesser degree, medializes the vocal process.
[89,90] Intraoperative voice evaluation is generally not possible.
Finally, injection may be insufficient in cases of advanced vocal fold
atrophy and fibrosis. [67]

Teflon injection is essentially irreversible. Although Dedo
reported removal, [46] the effects of vocal fold scarring after removal
would seem to lead to a poor voice quality. Voice results are variable
due to the low elasticity of Teflon and the inflammatory reaction with
fibrosis that results. [76] Reproducible results seem to be attainable
after much surgical experience. Laryngeal granuloma is frequent (see
below), and extrusion and mucosal ulceration are possible. [74] Teflon
has been shown to migrate to regional lymph nodes and even to distant
organs. [76]

Autologous fat is the ideal implant in its abundance, low cost, and
perfect biocompatibility. [89] Its viscosity is close to that of
laryngeal mucosa, increasing the ease of phonation after injection
compared with other materials. [77] Fat has been shown, however, to be
resorbed to an apparently unpredictable degree. Hoffman and McCulloch
have reported persistence of fat in the vocalis muscle after 5 months.
[45] Others have found a persistence of vocal fold augmentation in 30 to
40% of cases after 12 months. [65,85,91] In cases of resorption with an
adverse effect on voice, fat can always be reinjected, and previous fat
injection does not preclude the use of other medialization techniques
later. [45]

Indications. The irreversibility of Teflon and its potential
complications tend to limit its use today. Teflon is indicated only when
the paralysis is judged to be irreversible and favorable synkinesis has
not occurred. The rapidity of injection makes it an ideal substance in
case of poor general health or poor prognosis, as granuloma tends to
arise after several months or years (see below). Teflon is
contraindicated if spontaneous recovery or synkinesis is to be expected,
as it is irreversibly injected and can lead to poor vocal outcome.
Inflammatory disease of the larynx is also a contraindication, as Teflon
promotes local chronic inflammation. [76,83]

Because of its potential resorption, autologous fat is especially
indicated as a temporary symptomatic treatment for swallowing and voice
while awaiting spontaneous recovery with synkinesis. [92] Fat injection
can also be considered as a therapeutic trial before another
medialization technique or injection with an irreversible material.

Complications. As stated above, granuloma is the most frequent
complication of Teflon injection. It appeared after 6 months and up to
several years following injection for 36% of patients in the series
reported by Gardner et al. [93] Airway obstruction with stridor occurs
within the first few days after injection and seems to be most often due
to overinjection. [46,93] This complication can require tracheotomy or
reintervention for the removal of Teflon. Teflon can be dislodged or
displaced within the larynx, and it also tends to migrate to regional
lymph nodes and distant sites. [45,76,90]

Injection of autologous fat seems to have few complications, the
most frequent being hematoma and infection at the site of fat harvest.
One case of vocal fold pseudocyst has been reported after injection
superficially into the superficial lamina propria. [87]

Results. Autologous fat has been routinely employed with success in
treating aspiration due to URLNP. [65,87] Excellent vocal results have
also been reported. [90,91,94] Voice that is excellent initially tends
to deteriorate during the first 3 months and then stabilize for the next
3 to 9 months. [91] If lasting results are not obtained, reinjection or
another medialization technique is indicated. Finally, injection
addresses the anterior glottis better than the posterior glottis. [94] A
laryngeal configuration with a large posterior glottal gap would
probably benefit from associated arytenoid adduction.

Laryngeal reinnervation techniques

Introduction. The first description of laryngeal reinnervation is
attributed to Frazier and Mosser in 1926. [84] The aim of reinnervation
is to increase the motor afferences to the TA muscle to maintain at
least muscular tone and volume. Reinnervation can be performed by direct
end-to-end anastomosis with a nerve-muscle pedicled flap (strap muscle)
or by direct electrical laryngeal stimulation. Reinnervation is said to
decrease the glottal gap and improve the vibratory characteristics of
the paralyzed vocal fold. Most of these techniques are still
experimental and are generally associated with other techniques of
medialization when a predictable vocal result is necessary. [84,95]

Surgical techniques. End-to-end anastomosis is performed between
the proximal end of the recurrent laryngeal nerve and the distal end of
the ansa hypoglossi on the paralyzed side. The suture is a typical nerve
anastomosis using epineurial microsutures (10/0 diameter, in general).
Dissection and preparation of the cut recurrent nerve may be long and
difficult if previous cervical surgery has been performed.

The nerve-muscle pedicled patch technique employs much the same
external approach as that used for thyroplasty. The cutaneous incision
is extended to the anterior border of the sternomastoid muscle. The
muscle is retracted laterally, and the internal jugular vein and the
ansa hypoglossi are identified. The latter is followed to its extremity
in the anterior belly of the omohyoid or other strap muscle. A muscle
fragment of approximately 1 [cm.sup.3] containing the nerve end is
isolated. This flap is inserted into a window made in the thyroid
cartilage, as for thyroplasty, with the internal perichondrium resected
to expose the TA muscle. Two or three small sutures fix the flap to the
muscle. Closure and postoperative course are the same as for
thyroplasty. [95]

The laryngeal pacing technique is still under experimentation in
animals due to several unresolved technical considerations. [96]
Electrode miniaturization is necessary, but it is difficult in that the
smaller the electrode, the higher the impedance, and thus the more heat
produced, leading to muscular bums. [97] The ideal source for the rhythm
of laryngeal pacing is still controversial; some employ the
contralateral larynx, others the CT muscle, and still others the
diaphragm. Complications are frequent: electrode displacement,
electrical interference, software deficiencies, inflammation, infection,
and laryngeal muscle damage. Reliability and tolerance as yet remain
insufficient for use in humans.

Advantages and disadvantages. Nerve anastomosis and the
nerve-muscle pedicled flap can be performed using local anesthesia,
avoiding general anesthesia and shortening hospital stay. Both
procedures can be associated with thyroplasty or arytenoid adduction in
a one-step procedure. [51,98] Both techniques serve to decrease vocal
fold atrophy. [98] Reinnervation seems to be less successful in cases of
longstanding paralysis with onset of muscular atrophy. [98] The muscular
patch has the advantage of selectively reinnervating the TA muscle, as
compared with end-to-end anastomosis, in which synkinesis involving
other laryngeal muscles may occur. The muscular patch also leaves the
recurrent nerve intact and thus allows synkinesis to eventually occur.
[69,98]

Reinnervation is not a widely employed technique. Dissection can be
long and require a certain degree of experience. Vocal results are
unpredictable and become apparent only after 2 to 6 months
postoperatively. [84,98] In theory, there is a risk of unfavorable
synkinesis for end-to-end anastomosis. Woodson attributes the variable
vocal results to a competition between spontaneous reinnervation with
synkinesis and the surgical reinnervation. [38] It seems, in fact, that
surgical reinnervation is unsuccessful if synkinesis is already present.
[84] Also, in order to obtain true abductor function, selective
reinnervation of the PCA by nerve fibers active during inspiration (the
phrenic nerve, for example) is necessary. The present techniques do not
furnish adequate specificity for this function. [39]

Indications. Today reinnervation is essentially indicated in
conjunction with other techniques for treating URLNP as a means of
decreasing vocal fold atrophy. [84] The main contraindication is the
surgeon's unfamiliarity with the technique.

Complications. Cervical hematoma and wound infection are the
principal complications, as with any type of surgery. Goding considers
an insufficient vocal result to be a complication of reinnervation when
used as a sole treatment. [99]

Results. According to Goding, satisfactory voice results were
obtained in 88 to 95% of patients treated with the nerve-muscle pedicled
patch. [99] Objective voice measurements (cepstral peak and jitter)
significantly improved in 12 patients 8 months after end-to-end
anastomosis in a study by Olson et al. [100] Laryngeal mobility on the
operated side is observed in 5 to 40% of cases to varying degrees. [99]
Vocal fold muscle tone is preserved or improved in the majority of
cases.

A summary of the advantages and disadvantages of the surgical
techniques is shown in the table.

Conclusions

Unilateral laryngeal paralysis can arise from many different
causes. Evolution of the paralysis is often unpredictable, inasmuch as
pathophysiology is still incompletely elucidated. Indications for
treatment depend on the symptoms associated with the paralysis, on the
general health of the patient, and on the skills and habits of the
surgeon. Thyroplasty and vocal cord injection are well known and widely
employed. Aspiration and poor voice quality are successfully treated by
these techniques. Arytenoid adduction and laryngeal reinnervation are
less widely employed, probably due to a more difficult learning curve
and possibly due to variable results, especially with reinnervation.
Laryngeal pacing is still under investigation for use in humans.

Progress in diagnosis and a better understanding of laryngeal
neurophysiology developed during the entire 20th century. The past two
decades have seen the advent of laryngeal surgery for URLNP and a more
widespread interest in objective acoustic and aerodynamic voice
evaluation. The 21st century is rapidly bringing miniaturization of
cameras, microphones, and aerodynamic gauges. Progress is being made
daily in computerized processing of acoustic information and digital
images. Oral communication and its dysfunctions are becoming an
important theme in clinical and laboratory research. In this "age
of communication," quality of life depends more and more on the
quality of voice and speech, a challenge for today's
otolaryngologists.